Highly cited article published in the Veterinary Quarterly in 1991.

In early 1991, the Dutch pig industry was struck by the so-called mystery swine disease. Large-scale laboratory investigations were undertaken to search for the aetiological agent. We focused on isolating viruses and mycoplasmas, and we tested paired sera of affected sows for antibodies against ten known pig viruses. The mycoplasmas M. hysonoviae, M. hyopneumoniae, and Acheloplasma laidlawii, and the viruses encephalomyocarditis virus and porcine enterovirus types 2 and 7 were isolated from individual pigs. An unknown agent however, was isolated from 16 of 20 piglets and from 41 of 63 sows. This agent was characterized as a virus and designated Lelystad virus. No relationship between this virus and other viruses has yet been established. Of 165 sows reportedly affected by the disease, 123 (75 per cent) seroconverted to Lelystad virus, whereas less than 10 per cent seroconverted to any of the other virus isolates or to known viral pathogens. Antibodies directed against Lelystad virus were also found in pigs with mystery swine disease in England, Germany, and the United States. We conclude that infection with Lelystad virus is the likely cause of mystery swine disease.

Changing cytokeratin expression patterns in diethylstilbestrol dipropionate-induced metaplastic lesions of the goat prostate.

Five-month-old male goats were treated with 25 mg diethylstilbestrol dipropionate (DES-DP) by a single intramuscular injection, causing characteristic histological alterations in the peripheral glandular epithelium of the prostate, resulting in squamous metaplasia. Using a panel of monoclonal and polyclonal cytokeratin antibodies on frozen tissue sections of control prostates, we were able to immunohistochemically distinguish between the normal secretory cells, which are positive for cytokeratin 18 as detected with the antibody RGE 53, and the scattered basal cells, which could be specifically stained by the antibody RCK 103. Cytokeratins indicating squamous differentiation, i.e., nos 4 and 13, recognised by the antibodies 6B10 and 1C7, respectively, were found in sporadic cells throughout the normal goat prostate. Profound changes in cytokeratin expression were observed in the metaplastic lesions as compared to control peripheral glandular tissue. In this respect three monoclonal antibodies are of special interest. RCK 103 is immunoreactive with resting and all stages of differentiating basal cells. Antibodies 1C7 and 6B10 strongly stain the squamous cells in the metaplastic lesions, with 1C7 staining all the squamous cells in the lesions except the basal cell layer, and 6B10 being immunoreactive with the same suprabasal cells or the more differentiated cells in the upper strata. As a result the number of cytokeratin 18-positive cells is drastically reduced upon metaplasia. The results indicate that the goat system can be used as a suitable model system to further test the applicability of immunohistochemical methods in meat inspection and toxicological pathology.

[Endometrial cups in horses]. / De endometriumcups bij het paard.

Endometrial cups in horses are outgrowths appearing in the uterine wall of the pregnant horn between approximately 38 days and 150 of gestation. The cups are structures which vary in shape from oval to irregular and have distinct raised edges, showing an ulcer-like form. The maximum measurements are approximately 5 X 2.5 X 2.5 cm. Microscopic examination shows that they consist of large epithelioid decidual-like cells having large nucleoli. Pregnant Mare Endometrium Gonadotrophin (PMEG) is produced in the endometrial cups. PMEG may be regarded as a precursor of Pregnant Mare Serum Gonadotrophin (PMSG), which can be detected in the blood of mares. The exact function of PMSG is still obscure; some possible functions are suggested in the present paper. After approximately 70 days of gestation, regression starts. The regression of the cups is an immunological process in which the cellular branch of the immunological system plays an important role. Humoral immunity plays a more protective role in the process of regression, probably as a result of the production of 'blocking' antibodies.

[Mycotic placentitis in cattle]. / Mycotische placentitis bij het rund.

Two cases of bovine mycotic placentitis are reported. The two cows did not show any clinical symptoms before or during premature delivery of two clinically normal calves. In both placentas a severe placentitis accompanied by extensive necrosis and a large number of hyphae was present in two placentas. Aspergillus fumigatus was isolated in one case. The literature on bovine mycotic placentitis is reviewed in the discussion.

Comparative pathology of endometrial carcinoma.

A review is given of the comparative pathology of endometrial carcinomas regarding the incidence, the morphology, and the relation with endometrial hyperplasia. Compared to man, endometrial carcinomas in animals are fairly rare, except in rabbits, in cattle, and in a stock of Han: Wistar rats. In rabbits the endometrial carcinomas are mostly primary multiple and present in both horns. Histologically they are almost always adenocarcinomas. The histological structure can vary considerably with regard to the degree of differentiation. In cattle the endometrial carcinomas are mostly singular. Histologically they are mostly adenocarcinomas, often accompanied by formation of much dense fibrous tissue. In rats the endometrial carcinomas are mostly primary multiple adenocarcinomas. In man as well as in the rabbit and in the rat, relationships have been described between endometrial hyperplasia and endometrial carcinoma. It is striking that in the dog, a species in which endometrial hyperplasia very often occurs, endometrial carcinomas should be rare. The endometrial carcinoma in the rabbit as an animal model for human endometrial carcinoma is discussed extensively. In both species there are signs indicating relationships between endometrial carcinomas and sex hormones, especially oestrogens. The incidence in rabbits is very high. Endometrial carcinomas in rabbits can be transplanted subcutaneously in the same rabbit. They can also be cultured in vitro. Moreover the rabbit is a suitable species to study the progesterone/progesterone-receptor complex by determining the synthesis of the progesterone-induced protein uteroglobin which may be important in studying endometrial carcinomas. Uteroglobin is a good marker for a functional 'Progesterone-PR-DNA-mRNAug-Uteroglobin- System' (or PUG-System).(ABSTRACT TRUNCATED AT 250 WORDS)

Pseudohyperparathyroidism associated with perirectal adenocarcinomas in elderly female dogs.

In 8 elderly female dogs a syndrome of hypercalcaemia and hypophosphataemia was found in association with a perirectal adenocarcinoma. Following removal of the tumour the hypercalcaemia resolved within two days in four of the five operated animals.